This is a program project which seeks to understand the biology and immunology of certain sexually transmitted diseases. Emphasis is placed on Neisseria gonorrhoeae and Treponema pallidum. The objects of the research are to understand the genetics, physiology, surface structure, and host response to the gonococcus and Treponema pallidum. A variety of techniques are used including microbial genetics and hybridoma technology. Appropriate animal models are used for both gonococcal and T. pallidum infections; human serum, neutrophils, lymphocytes, and genital secretions are also analyzed to determine the nature of the host response. By use of genetics, immunological techniques, and analysis of surface chemistry attempts are made to identify the biological importance of individual cell envelope components of both the gonococcus and T. pallidum. This is an integrated program project. One of the component grants is now carried on at The University of Texas-San Antonio under the direction of Dr. Joel Baseman. This grant is a subcontract of the parent grant to the University of North Carolina. Five other grants are housed at the University of North Carolina. Of these one deals with Treponema pallidum and four with the biology, immunology, and physiology of the gonococcus.